Aerated gradual reduction flour milling system



May 4, 1954 c. A. MCELEVEY AERATED GRADUAL REDUCTION FLOUR MILLING SYSTEM Filed May 22, 1952 l WHAAT f/vraes M 2M WW5 Y P 5 a w 4 a M. H h J\ D E Z a E z a a LII... 8 7 WW 5 z w 2 H v m M L [A W. 9 00F 9 n n m% 13 (a n u 6 W C h m L 4 L M r 7 a 2 A 4 5 1 & I f 2 u u S N 0 a M; L C E I 007 i Mes INVENTOR.

ATTOA /VB J Patented May 4, 1954 UNITED STATES PATENT OFFICE AERATED GRADUAL REDUCTION FLOUR MILLING SYSTEM 5 Claims. 1

My invention relates to improvements in a gradual reduction fiour milling system for aerating the various machinery utilized in the milling of flour, and has for its purpose to both increase the efiiciency of the aeration of the stock streams as they pass through the iiour mill, and to effect a substantial saving of the higher grades of stock picked up by the air streams which, under present conditions, end up as feed or low grade stocks.

This application is a continuation-in-part of my pending application Serial No. 673,123, filed May 29, 1946, and entitled Method of Aerating Flour Milling Equipment."

Flour milling as it is understood today, is based on an arrangement of equipment to arrive at the end product. The Wheat berries are introduced into the head end of the mill and after a number of reductions and classifications, the several products and by-products merge as a result. It is not possible to totally break the Wheat berry down in one operation because of the differences in the physical characteristics of the wheat berry at different levels. The exterior shell of the wheat berry is not desirable for good flour. The next immediately underlying portion of the berry (perhaps 40 to 50 per cent of it towards the heart), makes a very high grade flour; whereas the portion of the berry around and including the heart makes a lower grade flour. For this reason, equipment within the flour mill usually is arranged to provide a plurality of stock streams, in each of which the berries are reduced to a desired predetermined extent. Usually there are five or six reductions; that is, five or six separate grade streams through which the wheat berries pass in the milling process. For illustration, the average mill has a first, second, third, fourth and fifth break; middling rolls; and tailed rolls. Each separate stock stream may include varying types of equipments such as rolls or breaks, sifters, purifiers, etc. The products tailed over from one stock stream are conveyed by various methods to the next grade stock stream in line.

In the milling operations through the various machines in the several grade stock streams, it is necessary to have certain quantities of air for evaporative cooling and aspiration. The standard practice of providing air for this purpose is, and for many years, has been to base the air requirements upon the total group of fiour milling equipment involved, irrespective of and without regard to the number of stock grade streams being aerated by a given air stream. For example, in a flour mill having all of the breaks on a given floor, it would be common practice to aerate all of the breaks by a common air stream with a result that the air stream would so commingle stock from the first, second, third, fourth and fifth breaks, and so on, that it could not thereafter be economically separated. Consequently, all'such stock is run into the feed or low grade stock streams where it brings a price far below the prices which the various constitucuts of the air stream would bring if they could be separated.

In order to avoid this loss, fiour mill designers lean over backward in an efiort to hold to a minimum the volume of air used in aerating milling equipmentwith a result that frequently less air is provided than is required to do the job efficiently.

I have, by considerable experimentation, learned that by aerating each of the several stock streams in a flour mill, by an independent air stream, and returning i. e., conveying the stock picked up by each of said air streams, to the same stock stream or a higher grade stock stream from which it was removed that not only can a substantial saving of high grade flour be effected, but also that an increased volume of air can be used where and if desired.

The above and still further highly important objects and advantages of my novel method will become apparent from the following detailed specification, appended claims and attached drawing.

Referring to the drawing, the single view is a diagram illustrating the fiow of stock through various components of a conventional flour mill and the manner in which my novel method is employed.

The preliminary treatment of the grain prior to the breaking of the wheat berries and including the cleaning, scouring, tempering etc, of the grain berry in itself does not comprise the instant invention. Hence, for the sake of brevity, equipment utilized in the above mentioned operations is not shown nor is it deemed necessary for further description, said operations being conventional and achieved by conventional methods and means.

The mill illustrated includes a breaking system comprising a plurality of breaking rolls l to 5, inclusive, each breaking roll feeding to a respective bolt or sifter unit, said units being indicated at 6 to Ill, inclusive. A purifier system includes a plurality, in this instance four, of purifiers H, [2, I3 and I l. The purifiers receive endosperm particles from the breaking system and separate the same. From thence, the screenings thereof are conveyed to a middlings reduction system comprising a plurality of reduction rolls IE to 24, inclusive. Each set of reduction rolls of the middlings reduction system is associated with and feeds stock to a respective bolt or sifter to 3 1, respectively. The tailings from the several purifiers II to [4, inclusive andfrom: several of the middlings reduction. units are conveyed to a first of a series of tailings reduction rolls 35, 38 and 3'! of a tailings reduction system comprising said tailings' reduction rolls and respective associated. belts or sifters 38, 39 and 4B.

As the wheat enters the first break rolls i from the head end of the mill, thehull of the" Wheat berry is broken to expose the-endosperm.. During the breaking operation, the Wheat germ is released and separated from the stock stream by suitable means, not shown. The stock stream istsubject to the-sifting or. separating equipment inithesifter 8, at portionv of the tailings thereof being: conveyed tothe purifier H, as indicated by: the: dotted flow line t]. Other tailings: are conveyed to theisecondbreak rolls=2, asindicated by the fiow line 42, Still other tailings are delivered to: the second purifier i2, as indicated by thedotted fiow line 43. The screenings from the sifter' G emerge. at. M in the nature of grade 13* flour ini relatively small amounts. The material received by the break rolls 2 is. fed to the sitter 1 from whence: tailings' are delivered to" the next breakrolls as-indicated by a flow line 55, where. they are further reduced and subject to thEiECtlOIl-IOI thesiiter 8i Certain-of the tailings from the: sifter' 8 are delivered to-the break rolls 4, as indicated by the flow line it, where the material is-further reduced and subjected to the action of the sitter 9 which delivers tailings to the" break rolls 5; as. indicated by a flow line- :23. From the final break rolls 5; material is fed to the sifter Hi associated therewith which. tails oifabranny material used as feed, as indicated by awfiow' line 48. A certain portion of the tailings fromthesifter T are carried to the purifier. H, as indicatedby a flow line 49 and a portion of flow line 4!. Other tailings from the bolt or sifter t are carried to the second purifier 12-, as indicated-by-afiow line 59 and part of the flow line .3. of tailings: from the bolt 8. are delivered to the purifier l2, as indicated by a flow line 5i and a portionof the-flow line 4-8, While another portion or grade of tailings from the-bolt or'siiter B- is delivered to-a third purifier It, as indicated by a now line- 52. The screenings from the sitters T and 8, like those of the sifter 6, comprise a B grade flour: and are discharged from their re speetiveisifters; as indicated at 53 and 54. Certain of the tailings from the sifter 9- are delivered to the: purifier It as indicated by a fiow line 55. The:- screenings from the sifters 9 and I!) comprise alower or C grade hour and are discharged as indicated: at 56 and 5?, respectively. From the above,.it will be seen that stock fiows in a stream from the sitter t through the break rolls 2, 3, 4 and 5 and the sifters associated therewith, the products of which comprise grades B and C flour, the branny feed and the'like being tailed off as indicated at. 68.

Fromthe purifier H, the endosperm particles aredelivered to the reduction rolls i5, as indicated-by a flow line 58, where they are broken up and subjected to the action of the sitter 25, the screenings thereoi comprising grade A or patent In like manner, a certain portion or grade I flour and discharged as indicated at 59. Some of the more branny particles are tailed. off from the sifter 25 and delivered to the reduction rolls 35 of the tailings reduction system as indicated by a flow line 60. Other tailings from the sitter 25 are delivered to the reduction rolls [6 as indicated by a flow line 6 I. Material passing through the reduction rolls I6 is subject to the action of the. sifter 26; some of the tailings therefrom being delivered to the tailings reduction rolls 35,

as indicated by a flow line 62 and a portion of the flow line 60. These tailings also contain br-anny particles: Other portions of the stock from-i the sifter 26 are tailed off to the reduction rolls H, as indicated by a flow line 83 where they arefurth'er' reduced and subjected to operation of. the sifter 2.1. A portion of the tailings from the sif'ter 2'! are delivered to the tailings reduction' rolls 35, as indicated by a flow line 84 and part of the flow line 60, Whereas the tailings fromthe sitter 21' are; delivered to the middlings reduction. rolls iii; as indicated by' a flow line 85; The stock stream passing through the reduction rollsl8 is subject to the action of the sifter 28, sorneof the material being tailed 01f therefrom and, delivered to the.- first taillngs reduction rails 35, as indicated by flow line 6G anda portion of the lines. 64. and Gil; The balanceofthe tailings from the sifter ZG-isdelivered to the reduction rolls [9, as indicated by a flow line Glfrom whence the tailed over and further reduced stock. is subjected to' the operation of thesifter 29; Like the-screenings from the sitter 25, the screenings I'romthe sifters- 26'to 29: inclusive, comprise grade A or patent flour and aredischarged-from the several sitters.- as: indicated-atiiil; 69,10 and 71, respectively. It should be noted: that the' stock stream resulting. in. the grade A fiour is-fedto the middlings reduction rolls l5'to 18 inclusive, not only from the purifier H but also from the purifiers l2 to M, inclusive. A portion ofthe material discharged by the purifier I2 is deliveredto the first'middlings reduction-rolls i5, as-indicatedby a flow line i2. and part ofv the flow line. 58; Another portion of the material discharged by the purifier. H!v is livered to the reduction rolls 1-6, as indicated by a flow line. 13. The reduction rolls l6 also receive material from thepurifier I3, asindicatcd bythe portion of the flow line 13 and afiow line 14. Other portions of material discharged by the-purifier [3- are delivered directly to the reduction rolls H, as indicated by a flow line 75, said rolls H also receiving a portion of the discharge from the purifier [4,. as indicated by a flowline 16 and part of the flow line 15. The balance ofthe material discharged from the purifier His delivered directly to the reduction rolls [8, as indicated by flow line H. From the above-itwill be seen that the material delivered to the middlings reduction rolls l5to 58 inclusive f-romv their associated purifiers and to each of the reduction rolls- IE to I9, inclusive, together with. their respective sitters, comprises a stock stream resulting in grade A flour.

The purifiers H to M, inclusive, discharge tailings of a lower grade than that requiredfor gradeA fiour and suchv material is conveyed or delivered to the whims reduction system. As shown, some of these tailings are delivered from thepurifier. H to the tailings reductionv rolls as indicated by a flow line 18- and a part of the flow line 50. The above mentioned material di charged from the-purifiers. I2, l3 and it is con. veyed asindicated by respective flow lines 19.,

and 8| which merge with the flow indicated by the line 18.

Certain of the tailings discharged by the sifter 29 are delivered to the middlings reduction rolls it, as indicated by a flow line 82 from whence they are subjected to the action of the sifter 30, the screenings therefrom discharged as grade B fiour, as indicated at $3. The sifter 3G discharges tailings which are delivered to the next reducing rolls 22!, as indicated by the flow line 84, from whence the material is received by the sitter 3!. The screenings discharged by the sifter 3i emerge as grade B flour at 85. Tailings discharged from the sitter 3! are delivered to the next middlings reduction rolls 22, as indicated by a flow line 85, and from thence to the sitter 32 associated therewith, the resultant screenings of which emerge as grade B flour, as indicated at 87. The middlings reduction rolls to 22, inclusive, and their associated sitters to 32, inclusive respectively, operate on a stock stream which, although being a combination of the stock stream which provides grade A or patent flour, may be assumed to be and is treated as a separate stock grade stream in that it produces a different grade flour, namely grade B flour. The last sifter in this namely the sifter 32, discharges tailings which are delivered to the mi-ddlings reduction rolls 23 as indicated by a flow line 83, from whence the material is received by its associated sifter 33, the screenings of which emerge at 89 as grade C flour. The tailings discharged from the sitter 33 are conveyed to the final middlings reduction rolls fi l as indicated by a flow line 90,

from whence they are received from the final sitter 3 associated therewith. The product of the sifter 3t emerges as grade C flour at 9!.

The tailings received by the first tailings reduction rolls 35 from the several purifiers and the middlings reduction sitters 25 to 28, inclusive,

re further reduced and subject to the action of the sifter it, the screenings of which emerge as grade B flour, as indicated at 92. The tailings from the sitter 38 are delivered to the second tailings reduction rolls 36, as indicated by the how line 93. It should here be noted that a certain percentage of the tailings from the final siiter in the series which produces grade A flour, namely, the sitter 2%, is delivered to the second tailings reduction rolls 35, as indicated by a flow line it. The sifter 39 receives material passing through the reduction rolls 36 and produces grade C flour discharged therefrom as indicated at as and tailings which are delivered to the final tailings reduction rolls S'l, as indicated by a flow line as. The final sifter GB in the tailings reduction system also produces grade C flour, as indicated at 3?.

In the drawing, the various flow lines indicating the flow of stock through the mill in the prochiciru of the various grades of flour, feed and the like, is indicated by relatively light dotted or broken lines. It should be borne in mind that the above described arrangement is but one of a number oi arrangements of flour milling equipment. The means for conveying the stock through the mill, such as conveyor ducts, belts, elevators and the like are indicated broadly by the flow lines above described, such equipment being conventional.

My improved method of aerating flour milling equipment utilizes a plurality of centrifugal separating devices and associated motor-driven fans or blowers connected by suitable conduits or the like to various component elements of the milling equipment in such a manner that particles of stock held in air suspension in said components in each of a plurality of stock streams will be removed separately by separate air streams generated by the fans and settled-out in the centrifugal separators, the settled-out stock or flour constituents being delivered to the same stock grade stream from whence it was taken, or a higher grade stock stream from whence it was removed. In the diagram illustrated, this arrangement is carried out through the entire system illustrated, with a single exception, that exception being the aeration of the first break rolls l and the sifter 6 associated therewith. In this case, the settled-out flour is not returned to a stock stream, but is delivered by conventional means, not shown, to a suitable destination for packaging or other treatment.

The stock stream flowing through the middlings reduction rolls I5 to [9, inclusive, and their associated sifters or separators 25 to 29, inclusive, respectively, is aerated by a fan 98 which may be assumed to be driven by a motor, not shown, and which delivers the air to a centrifugal separator 39 of conventional design. The flour-laden air is drawn by the fan 98 from the various machines in the stock stream which provides grade A flour through a duct system including a main conduit It!) and a plurality of branch conduits it! connecting the main conduit lili) with the several middlings reduction rolls [5 to It, inclusive, the sifters 25 to 29, inclusive, and other equipment associated therewith but not shown. As shown, the conduits and I Eli are indicated by relatively heavy solid lines in the drawing. The flour which is settled-out in the centrifugal separator 99 is delivered by suitable means to the final reduction rolls !9 of the group of equipment which produces grade A or patent flour as indicated by the heavy broken or dotted flow line Hi2 and a portion of the flow line 61. Similarly, the stock grade stream of the middlings reduction system which produces grade B flour, namely, the reduction rolls 20 to 22, inclusive, the associated separators 30 to 32, inclusive, and other related equipment, not shown, is aerated by a separate air stream generated by a motor-driven fan lc3 which draws flour-laden air from said equipment through a main conduit Hi4 and branch conduits M5. The fan H33 delivers the flour-laden air to a centrifugal separator Hi6 from whence the settled-out flour is returned to the final reduction rolls 22, as indicated by the heavy dotted or broken flow line N31.

The stock stream passing through the first break rolls l and the sifter or separator ii associated therewith, is aerated by an air stream generated by a motor-driven fan H18, as indicated by a heavy solid flow line 5539. The fan I08 feeds the flour-laden air to a centrifugal separator I it, the flour settled-out therefrom being a grade D or feed flour. As above stated, this fiour is conveyed by suitable means to a point for further treatment.

The remaining sets of break rolls 2 to 5, inclusive, and their associated sitters l to It, inclusive, are aerated by a common air stream generated by a motor-driven fan ill connected to said break rolls and sifters by suitable conduit means indicated by a relatively heavy solid flow line H2 and branch conduits illustrated by flow lines I I3. Bearing in mind that the sitters l and 8 produce grade B dour, whereas the sifters 9 and I0 produce grade C flour, a loss of savings would occur if the flour gathered from these machines: were discharged to a stock streamsof the lower-grade such as produces grade C flour. In thisinstance; however, the flour gathered by the fan Ill is settled out in a centrifugal separator H4 and delivered to equipment which results in grade B flour, namely, th first tailings reduction rolls 35 and the sifter' 38'. As shown by the relatively heavy dotted flow line I Wand portions of the-flow lines 18 and 5B, the settled-out flour is delivered. to a point'where it will be separated to provide grade B'and grade C flour. Such combining of the stock streams is permitted where the quantity of hour is not too great and where separation thereof-is not too difficult. Such an arrangement is also sometimes dictated by the lay-out of the millandth'e possible expense involved in setting up the aerating equipment. In the arrangement illustrated, it will be'seen that the fan Ill and separator H4 aerate the rolls 23..and 24 and sifters 32 and 3d of the middlings reduction units which produce grade C flour as well as the entire tailings reduction system as illustrated by a portion of the flow line i i2, a flow line I I5 and branch'lines I IT.

The particles of material or flour in air suspension in the purifiers H to I 1", inclusive, are drawn by a fan I if; through a conduit illustrated by'a flow line H and branch conduits me, and fed to a centrifugal separator 25 from whence the settled-out flour i delivered to the tailings reduction rolls 35, as indicated by a heavy dotted flow line I22; aportion of the ficw lines H5, 12 and'fifi.

With the above arrangement, I am able to employ a greater volume of air at pressures surficient to thoroughlyiaerate the various machines and equipment in .aflour mill system and I have found that savings up to two per cent (2 9b) of high grade flour removed from the stock streams can be effected, such high grade flour heretofore having gone into the lower grade stock or 186d streams because of the diiliculty of separation.

What'I claim is:

1. In a gradual reduction flour milling system comprising a breaking system having a series of set of break rolls and a corresponding series of sifters producing grade A flour, middlings and tailings; the improvement comprising in combination with said break rolls and sifters, of a middlings reduction system having a first grade A flour producing section and a second grade B flour producing section, each of said sections including a series of sets of break rolls and corresponding sifters, a ventilating means for said gradual reduction system comprising at least two suction fans and cooperating eparators, one fan and its separator having an air inlet connection with the rolls and sitters of said first section and the other fan and separator having an air inlet connection with the rolls and sifters of said second section, and each of said separators having means for returning the collected product to a set of rolls of its reduction section, whereby an increase in the production of grade A flour from said breaking system is efiected.

2. In a flour milling system asdeiined in claim 1, in which the middlings reduction system also includes a third grade C flour producing section having a series ofsets of break rolls and corresponding sifters, a. tailings reduction system having a-series of sets of break rolls and corresponding sifters, and said ventilating means includes another suction fan and corresponding separator, said fan having an air inlet connection with the rolls and Sifters of said third section and also the rolls and sifters. of said tailings reduction section, and said separator having means for conveying the product collected thereby to one of said'sets of rolls of saidtailings reductionsystern.

3; In a flour milling system as defined in claim 1, and having a tailings reduction system including a series. of sets-0f breakrolls and corresponding Sifters, and wherein said ventilatin means includes another suction fan and cooperating separator, means connecting the air inlet of said fan with the sets ofbreak rolls and sifters of said breaking system, and said separator having mean for conveying the product collected thereby to one set of said. sets of break rolls of said tailings reduction system.

4. In a flour millingsystem as defined in claim 3, wherein the inlet or" said fan is connected to the rolls and sifters of both. the breaking system and the-tailings reduction system.

5. In a flour milling system as defined in claim 4, wherein a series of purifiers is interposed between the series of sifters of the breaking system and the series of sets of rolls of the-first section of the middlings-reduction system and delivering grade A flour to the latter; and said ventilating means includes a further suction fanand cooperating separator; said fan having means connecting the air inlet thereof to said series of purifiers, and said separator having means conveying the products collected therebyto one of said sets of rolls of said tailing reduction sys tem;

Gradual Reduction Milling, by Gibson, publ. by C. M. Palmer, 1885, Minneapolis, Minn, pages 225, 226.

Provender Milling, by J. F; Lockwood, publ. 1945 by Northern Publishing Co., Lt.; New York, 230 Produce Exchange; pages 274, 275. 

